In the semiconductor industry, an integrated circuit that is designed and verified to provide certain functionality is treated as an intellectual property (IP). As the rapid development in IC design and manufacturing, more and more transistors are packed into a single chip. Conventional starting-from-scratch IC design approaches are unable to develop an IC comprising millions of logic gates or more in a short period of time to meet the market demands. Instead, by integrating one or more IP modules into a single chip, the IC developers can design chips that provide multiple functions a complete system, called system on a chip (SOC). For example, a chip used in computers may comprise a CPU module, a modem module, and a LAN module. The SOC design approach not only reduces the number of components and PCB cost, but also reduces the chip size and power consumption. With the demands of better, faster and cheaper designs, the reusability of IP becomes an important practice to shorten the development time, and reduce the overall cost.
In general, every IC includes a testing circuit for testing if the IC functions correctly. When the testing circuit is activated by a testing activation signal, it receives a testing signal, and generates a testing result. The test result is then interpreted to determine if the IC functions correctly. This is particularly important as a correctness test can only be performed in this way after the IC is packaged. It is, therefore, necessary to include the testing circuit of an IP module when that IP module is used in a design so that its correctness can be tested as well. However, as it is technically easy to copy IP modules, and as the concept of IP protection is still in its infancy, unauthorized use of IP modules is common, and difficult to prevent. Furthermore, when an IP module is incorporated into a chip design, it is difficult to identify the IP core from the finished layout, especially after the steps of synthesis, placement and routing. Current technology does not provide appropriate method for detecting and verifying the use of an IP module. This lack of IP protection may further inhibit the development of the industry.